The Los Angeles Times is reporting that the dramatic rise in pot farms in Northern California is starting to take a toll on the surrounding environment. Agricultural practices like water-siphoning, pesticide spraying, and littering are having a noticeable effect on what is a very fragile ecosystem.

Marijuana farms are definitely on the rise. In one 37-square mile patch of forest, state scientists counted no less than 281 outdoor pot farms and 286 greenhouses containing an estimated 20,000 plants — most of which are being fed by water diverted from creeks or the Eel river. The scientists estimate that the farms are swallowing up to 18 million gallons from the watershed every year — and at a time when salmon most need it.

The LAT reports:

Because marijuana is unregulated in California and illegal under federal law, most growers still operate in the shadows, and scientists have little hard data on their collective effect. But they are getting ever more ugly snapshots.

A study led by researchers at UC Davis found that a rare forest carnivore called a fisher was being poisoned in Humboldt County and near Yosemite in the Sierra Nevada.

The team concluded in its July report that the weasel-like animals were probably eating rodenticides that marijuana growers use to keep animals from gnawing on their plants or were preying on smaller rodents that had consumed the deadly bait. Forty-six of 58 fisher carcasses the team analyzed had rat poison in their systems.

Mark Higley, a wildlife biologist on the Hoopa Indian Reservation in eastern Humboldt who worked on the study, is incredulous over the poisons that growers are bringing in.

"Carbofuran," he said. "It seems like they're using that to kill bears and things like that that raid their camps. So they mix it up with tuna or sardine, and the bears eat that and die."

The insecticide is lethal to humans in small doses, requires a special permit from the EPA and is banned in other countries. Authorities are now regularly finding it at large-scale operations in some of California's most sensitive ecosystems.

It is just one in a litany of pollutants seeping into the watershed from pot farms: fertilizers, soil amendments, miticides, rodenticides, fungicides, plant hormones, diesel fuel, human waste.

Scientists suspect that nutrient runoff from excess potting soil and fertilizers, combined with lower-than-normal river flow because of diversions, has caused a rash of toxic blue-green algae blooms in North Coast rivers over the last decade.